World number two Kerber was sensationally bundled out by a woman playing the event for the first time, with American Danielle Collins humiliating the Wimbledon champion 6-0, 6-2 in under an hour.

Wimbledon winner and 2016 champion Kerber, the bookies' favourite along with Serena Williams after defending champion Caroline Wozniacki was ousted early, was no match for Collins, ranked 35 in the world.

Collins is little known after playing much of her tennis in the US college system and was making her debut in the main draw at Melbourne Park. She had never won a Grand Slam match before this year.

Hometown hero Ashleigh Barty also made the last eight after muscling past Maria Sharapova and will next meet Petra Kvitova.

Sharapova claimed her biggest scalp since completing a drugs ban in 2017 when she rolled Wozniacki in round three and looked on track to carry the momentum forward.

The 30th seed won the first set but then fell to pieces, eventually succumbing 4-6, 6-1, 6-4.

Men's second seed Rafael Nadal, returning from foot surgery, barrelled past former world number four Tomas Berdych 6-0, 6-1, 7-6 (7/4) as he stays on track for an 18th Grand Slam title.

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